Quote Originally Posted by Linden View Post
Yes did it on my 620 (couple of years ago) must pop the top and have a look (it has done over 70,000km road since it was done) and this was an air cooled engine - from memory was meant to make engine cooler (my air cooled show +150C at EC in summer) and also add a bit of compression (we were shaving heads etc)

As for easy ... yes sent them off (well Gowanlochs did) and then they came back minus some of my money :(

I guess the effectiveness is up to the person talking ... I can't say if it helped my engine as we did so much but it was a great little motor at the time
Ok, interesting. I'd be interested to know how easy it'd be to do oneself and perhaps consider for next time.
This one is just a bit of a refresh, as it's running really well in all other respects.